Allow plugins to process user responses to their messages
Rather then only being able to respond to commands plugins should be able to perform stateful communication e.g.
endroid: What is your name?
user: Dave
endroid: Age?
user: 24
Currently this is difficult for plugins to achieve as they can only register to be notified of all messages, messages matching a reg exp or messages matching a command prefix.
To achieve stateful comms the following is proposed
* on message_send a plugin can provide response and no_response callbacks to mark that message as requiring a response
* endroid ensures only a single response_required message can be outstanding per 'sender' (person or room(?))
* on receipt of a message endroid performs its usual processing upto (but not including) calling any unhandled callbacks.
At this stage if there is an outstanding response_required message for that sender:
* if the message was handled call the message's no_response callback
* if the message was unhanded call the message's response callback with the message content as an argument.
Other considerations:
* Timeout on resp_required messages if no message is received from that sender after a while (perhaps configurable by the plugin but with a minimum).
* Could work in MUCs but might need to only consider messages with EnDroids's nick in them e.g. @EnDroid Dave, or be truly sender-specific (so EnDroid can sustain multiple conversations with different people at the same time in the same room).
Whiteboard
Proposed and implemented that we check the other way round: per 'sender = person', a single response_required message can exist (any subsequent addition of a message replaces the previous ones, although calling send_chat with callbacks None in the usual way won't overwrite the previous callbacks). If a response_required message is outstanding, Endroid attempts to handle the next message using that response_required callback. If the callback fails, we consider it 'unhandled' and pass to normal plugin handling. The response_required callback is then forgotten, whether or not it successfully handled the response.
This is in an attempt to reduce end-user confusion: context-aware plugins are *only* aware of what immediately follows the message which set up a context. Otherwise we could have two plugins simultaneously attempting to get user input, which could be hard for the user to navigate. Moreover, if we envisage the following:
Endroid: Please type '3'.
User: help
Endroid: EnDroid at your service!
User: 3
Endroid: Thanks for the 3
This seems a bit less intuitive than:
Endroid: Please type '3'.
User: help
Endroid: EnDroid at your service!
User: 3
Endroid: I don't recognise that command.
(since the intervening command `help` might have printed out long and complicated stuff, which intuitively resets context in the mind of the user.)
